Self-Heating and Reliability-Aware “Intrinsic” Safe Operating Area of Wide Bandgap Semiconductors – An Analytical Approach

The emergence of several technology options and the ever-broadening range of applications (e.g., automotive, smart grids, solar/wind farms) for power electronic devices suggest both a need and an opportunity to develop unifying principles to guide the development of wide bandgap (WBG) semiconductors. Unfortunately, power electronic devices are typically evaluated with a variety of elementary figure of merits (FOMs), which offer inconsistent/contradictory projections regarding the relative merits of emerging technologies. Indeed, one relies on the empirical (extrinsic) safe-operating area (SOA) of a packaged device to ultimately assess the performance potential of a technology option. Unfortunately, extrinsic SOA can only be calculated a posteriori, i.e., after precise measurement of the fabricated device parameters, making it suitable only for relatively mature technologies. Based on the insights of material-device-circuit-system performance analysis of a variety of idealized WBG power electronic devices (e.g., GaN HEMT, β-Ga2O3 MOSFET), in this paper, we analytically derive a comprehensive, substrate-, self-heating-, and reliability-aware “intrinsic/limiting” safe operating area (SOA) that establishes a priori, i.e., before device fabrication, the optimum and self-consistent trade-off among breakdown voltage, power consumption, operating frequency, heat dissipation, and reliability. We establish the relevance of the intrinsic-SOA by comparing its prediction with a broad range of experimental data available in the literature. In between the traditional FOMs and extrinsic SOA, the intrinsic SOA allows fundamental/intuitive re-evaluation of intrinsic technology potential for power electronic devices and identifies specific performance bottlenecks and how to circumvent them.